A Martian meteorite recently found on Earth may represent a missing link between Mars' warm, wet past and its present cold and dry state, a new study shows.

The meteorite  named NWA 7034  is markedly dissimilar from other meteorites from Mars that scientists have studied on Earth.

NWA 7034 has about 10 times more water content (about 6,000 parts per million) than any of the 110 other known meteorites that have fallen to Earth from Mars, suggesting that the meteorite probably came from the Martian surface, as opposed to deeper inside, said University of New Mexico planetary scientist Carl Agee, lead author of a paper describing the findings published in the Jan. 3 issue of the online journal Science Express.

Previously studied Martian meteorites, known as the SNC samples, appear to come from a different, less explored part of the Martian landscape. They probably broke away from Mars after a large asteroid impacted a certain region of the planet. But this newest sample is more representative of Mars's surface

The meteorite's age is also of interest to scientists. Most of the SNC meteorite samples date to only around 1.3 billion years ago, with the oldest being about 4.5 billion years old

The researchers confirmed the meteorite's Martian origins using a process of elimination...Mercury wasn't an option: the composition of the volcanic meteorite didn't match the surface of the closest planet to the sun. Venus didn't fit either. Scientists hypothesize that that planet's surface is too dry to produce a meteorite with NWA 7034's water content

“(SNCs) They are distinguished from other meteorites by their young crystallisation ages, down to 165 Myr. A young age implies formation on a body that was still active (i.e., not totally cooled and solidified) well after the initial accretion and aggregation of the Solar System ~ 4560 Myr ago. In other words, the SNCs must originate from a planet-sized body, not an asteroid.

The mechanism by which the meteorites reach the Earth is by impact ejection: as asteroids impact the martian surface, craters are formed. If the impactor enters the martian atmosphere at a sufficiently shallow angle and with a high enough velocity, then ejecta thrown from the surface can escape to orbit the Sun as small bodies in space, prior to landing on the Earth as meteorites.

The martian origin can be deduced through a process of elimination, by considering all the bodies in the Solar System in turn. Several of the planets can be rejected almost immediately. Mercury is too close to the Sun to allow ejecta to escape outwards to Earth. Jupiter, Saturn, Uranus and Neptune are gas planets, and not rocky. The satellites of the giant planets, although rocky in nature, are unlikely source objects, since any ejecta blasted from their surfaces will not escape from the gravitational attraction of their parent planet. Pluto is a mixture of rock and ice, as are comets, and are not thought to have been molten. So we are left with Venus, Earth and its Moon, and Mars.
Venus?

There is a low, but finite, possibility of Venus being the parent planet. Venus is about the same size and mass as the Earth, and so has a similar escape velocity.

But Venus has a very thick atmosphere with a high surface pressure (~ 96 atms). In order for ejecta to escape the planet, they must have very high energies when they are removed from the surface, such that by the time they have traversed the atmosphere, the ejecta still have sufficient velocity to escape. Similarly, the incoming impactor must be travelling at great speed, so that it is not decelerated so much that it is unable to impart sufficient energy to the ejecta to enable debris to escape.

And on top of all this, once material has escaped from Venus’ surface, it must have the correct orbital vectors to thrust against the gravitational tug of the Sun, and travel outwards to the Earth. Venus, therefore, is dynamically unfavourable as the parent of the SNCs.”

So this comment appears on every single thread on FR relating to a scientific discovery (in other cases, ususally with the implication scientists are just randomly making up information in hopes of getting funding.)

Scientists publish their results, and the interesting results are picked up and reported by the scientific media. Scientists that generate more interesting results get more funding than those that don't, just like Lawyers that win a lot of cases get more money than those that don't, realtors that sell more houses than others, chefs that make better food, etc.

I don't understand why scientists are somehow inherently more greedy or corrupted by the almighty dollar.

Nobody becomes a planetary scientist to make money - going through almost a decade of expensive education, at least, the majority end up with salaries trivial compared to doctors, lawyers, and b-school graduates.

You’d better be careful, a lot of people have an all-consuming hatred of anyone with any actual expertise or knowledge, or anyone that has any idea of what they are talking about; your post indicates this may be true.

this comment appears on every single thread on FR relating to a scientific discovery (in other cases, ususally with the implication scientists are just randomly making up information in hopes of getting funding.)

The funding comments are mostly reserved for the quack science articles, which clearly this is not.

That said, the funding comment may also be entering into FR lore, along with "All your base" and "I'd hit it" and "Not Guilty" as a throwaway comment just to be the first to say it.

-PJ

11
posted on 01/04/2013 9:57:39 PM PST
by Political Junkie Too
(If you are the Posterity of We the People, then you are a Natural Born Citizen.)

But Venus has a very thick atmosphere with a high surface pressure (~ 96 atms). In order for ejecta to escape the planet, they must have very high energies when they are removed from the surface, such that by the time they have traversed the atmosphere, the ejecta still have sufficient velocity to escape.

So how do they know what Venus's atmosphere was like 2 billion years ago?

I’ve seen “science” twisted for political gain over and over again. Ever hear of Global Warming?

This particular rock discovery just happens to be one of those discoveries that seems suspicious. Finding a rock on earth that happens to be from Mars pushes the realm of Art Bell. Is there a made in Mars stamp on the bottom of said rock?

The last time we had a rock (found in Antarctica ~1995) from Mars was soon discredited and the particular department was scheduled to be unfunded.

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